Hi,
Yes, the stamp check was added.
So the qemu emulator should return a suitable RSS BPF helper or nothing.
Each qemu emulator may have a different helper that suits it.
So, the idea is to ask for the helper from qemu.

On Tue, Aug 24, 2021 at 9:41 AM Markus Armbruster <armbru@redhat.com> wrote:

> Andrew Melnichenko <andrew@daynix.com> writes:
>
> > Hi,
> >
> >> The helper may or may not be installed at the path compiled into QEMU.
> >>
> > Yes, so the helper will not be called - QEMU will try to initiate eBPF
> RSS
> > or use "in-qemu" RSS.
>
> My point is: the proposed command's mission is to help the management
> application run the right helper.  However, its advice is *unreliable*.
> It may point to the wrong helper, or to nothing at all.  The right
> helper may still exist elsewhere.
>
> I suspect you're trying to address the problem at the wrong level.
>
> Similar versioning issues exist with other helpers.  We've been doing
> fine without QEMU providing unreliable advice on where they might sit in
> the file system.  What makes this one different?
>
> >> What happens when you use the wrong helper?
> >>
> > UB - in most cases, eBPF program will work with wrong configurations.
> > That's why the stamp was added.
> >
> > query-helper-paths checks the stamp only for RSS helper.
>
> I have no idea what you're talking about :)
>
> My best guess is that you're trying to tell me that attempting to work
> with the wrong helper will fail cleanly due to some stamp check.  That
> would be nice.
>
>